31,811 research outputs found
Segment-level evaluation of the simulated aggregation test: US corn and soybean exploratory experiment
An evaluation of the corn and soybean proportion-estimation accuracy and dot labeling accuracy of the Simulated Aggregation Test, U.S. Corn and Soybean Exploratory Experiment, is presented. These results are in turn compared with the corn and soybean proportion-estimation accuracy and dot labeling accuracy of the Classification Procedures Verification Test
A Basis for Interactive Schema Merging
We present a technique for merging the schemas of heterogeneous databases that generalizes to several different data models, and show how it can be used in an interactive program that merges Entity-Relationship diagrams. Given a collection of schemas to be merged, the user asserts the correspondence between entities and relationships in the various schemas by defining "isa" relations between them. These assertions are then considered to be elementary schemas, and are combined with the elementary schemas in the merge. Since the method defines the merge to be the join in an information ordering on schemas, it is a commutative and associative operation, which means that the merge is defined independent of the order in which schemas are presented. We briefly describe a prototype interactive schema merging tool that has been built on these principles. Keywords: schemas, merging, semantic data models, entity-relationship data models, inheritance 1 Introduction Schema merging is the proble..
Education alignment
This essay reviews recent developments in embedding data
management and curation skills into information technology,
library and information science, and research-based
postgraduate courses in various national contexts. The essay
also investigates means of joining up formal education with
professional development training opportunities more
coherently. The potential for using professional internships as a
means of improving communication and understanding between
disciplines is also explored. A key aim of this essay is to identify
what level of complementarity is needed across various
disciplines to most effectively and efficiently support the entire
data curation lifecycle
Implications of a new light gauge boson for neutrino physics
We study the impact of light gauge bosons on neutrino physics. We show that
they can explain the NuTeV anomaly and also escape the constraints from
neutrino experiments if they are very weakly coupled and have a mass of a few
GeV. Lighter gauge bosons with stronger couplings could explain both the NuTeV
anomaly and the positive anomalous magnetic moment of the muon. However, in the
simple model we consider in this paper (say a purely vectorial extra U(1)
current), they appear to be in conflict with the precise measurements of \nu-e
elastic scattering cross sections. The surprising agreement that we obtain
between our naive model and the NuTeV anomaly for a Z' mass of a few GeV may be
a coincidence. However, we think it is interesting enough to deserve attention
and perhaps a more careful analysis, especially since a new light gauge boson
is a very important ingredient for the Light Dark Matter scenario.Comment: 9 page
Strange quark asymmetry in the nucleon and the NuTeV anomaly
The NuTeV anomaly of a non-universal value of the fundamental parameter
sin^2\theta_W in the electroweak theory has been interpreted as an indication
for new physics beyond the Standard Model. However, the observed quantity
depends on a possible asymmetry in the momentum distributions of strange quarks
and antiquarks in the nucleon. This asymmetry occurs naturally in a
phenomenologically successful physical model for such parton distributions,
which reduces the NuTeV result to only about two standard deviations from the
Standard Model.Comment: 4 pages, 5 figures, RevTex4. Updated with new references and extended
discussion. v.3: Minor corrections mad
Neutrino mass in GUT constrained supersymmetry with R-parity violation in light of neutrino oscillations
The neutrino masses are generated in grand unified theory (GUT) constrained
supersymmetric model with R-parity violation. The neutrinos acquire masses via
tree-level neutrino-neutralino mixing as well as via one-loop radiative
corrections. The theoretical mass matrix is compared with the phenomenological
one, which is reconstructed by using neutrino oscillation and neutrinoless
double beta decay data. This procedure allows to obtain significantly stronger
constraints on R-parity breaking parameters than those existing in the
literature. The implication of normal and inverted neutrino mass hierarchy on
the sneutrino expectation values, lepton-Higgs bilinear and trilinear R-parity
breaking couplings is also discussed
Reconstructing Seesaws
We explore some aspects of "reconstructing" the heavy singlet sector of
supersymmetric type I seesaw models, for two, three or four singlets. We work
in the limit where one light neutrino is massless. In an ideal world, where
selected coefficients of the TeV-scale effective Lagrangian could be measured
with arbitrary accuracy, the two-singlet case can be reconstructed, two three
or more singlets can be differentiated, and an inverse seesaw with four
singlets can be reconstructed. In a more realistic world, we estimate \ell_\a
\to \ell_\b \gamma expectations with a "Minimal-Flavour-Violation-like"
ansatz, which gives a relation between ratios of the three branching ratios.
The two singlet model predicts a discrete set of ratios.Comment: 14 page
Nonlinear Electron Oscillations in a Viscous and Resistive Plasma
New non-linear, spatially periodic, long wavelength electrostatic modes of an
electron fluid oscillating against a motionless ion fluid (Langmuir waves) are
given, with viscous and resistive effects included. The cold plasma
approximation is adopted, which requires the wavelength to be sufficiently
large. The pertinent requirement valid for large amplitude waves is determined.
The general non-linear solution of the continuity and momentum transfer
equations for the electron fluid along with Poisson's equation is obtained in
simple parametric form. It is shown that in all typical hydrogen plasmas, the
influence of plasma resistivity on the modes in question is negligible. Within
the limitations of the solution found, the non-linear time evolution of any
(periodic) initial electron number density profile n_e(x, t=0) can be
determined (examples). For the modes in question, an idealized model of a
strictly cold and collisionless plasma is shown to be applicable to any real
plasma, provided that the wavelength lambda >> lambda_{min}(n_0,T_e), where n_0
= const and T_e are the equilibrium values of the electron number density and
electron temperature. Within this idealized model, the minimum of the initial
electron density n_e(x_{min}, t=0) must be larger than half its equilibrium
value, n_0/2. Otherwise, the corresponding maximum n_e(x_{max},t=tau_p/2),
obtained after half a period of the plasma oscillation blows up. Relaxation of
this restriction on n_e(x, t=0) as one decreases lambda, due to the increase of
the electron viscosity effects, is examined in detail. Strong plasma viscosity
is shown to change considerably the density profile during the time evolution,
e.g., by splitting the largest maximum in two.Comment: 16 one column pages, 11 figures, Abstract and Sec. I, extended, Sec.
VIII modified, Phys. Rev. E in pres
A comparison of soil moisture characteristics predicted by the Arya-Paris model with laboratory-measured data
Soil moisture characteristics predicted by the Arya-Paris model were compared with the laboratory measured data for 181 New Jersey soil horizons. For a number of soil horizons, the predicted and the measured moisture characteristic curves are almost coincident; for a large number of other horizons, despite some disparity, their shapes are strikingly similar. Uncertainties in the model input and laboratory measurement of the moisture characteristic are indicated, and recommendations for additional experimentation and testing are made
Ultrasonic locating devices for central venous cannulation: meta-analysis
OBJECTIVES: To assess the evidence for the clinical
effectiveness of ultrasound guided central venous
cannulation.
DATA SOURCES: 15 electronic bibliographic databases,
covering biomedical, science, social science, health
economics, and grey literature.
DESIGN: Systematic review and meta-analysis of
randomised controlled trials.
POPULATIONS: Patients scheduled for central venous
access.
INTERVENTION REVIEWED: Guidance using real time two
dimensional ultrasonography or Doppler needles and
probes compared with the anatomical landmark
method of cannulation.
DATA EXTRACTION: Risk of failed catheter placement
(primary outcome), risk of complications from
placement, risk of failure on first attempt at
placement, number of attempts to successful
catheterisation, and time (seconds) to successful
catheterisation.
DATA SYNTHESIS: 18 trials (1646 participants) were
identified. Compared with the landmark method, real
time two dimensional ultrasound guidance for
cannulating the internal jugular vein in adults was
associated with a significantly lower failure rate both
overall (relative risk 0.14, 95% confidence interval
0.06 to 0.33) and on the first attempt (0.59, 0.39 to
0.88). Limited evidence favoured two dimensional
ultrasound guidance for subclavian vein and femoral
vein procedures in adults (0.14, 0.04 to 0.57 and 0.29,
0.07 to 1.21, respectively). Three studies in infants
confirmed a higher success rate with two dimensional
ultrasonography for internal jugular procedures (0.15,
0.03 to 0.64). Doppler guided cannulation of the
internal jugular vein in adults was more successful
than the landmark method (0.39, 0.17 to 0.92), but the
landmark method was more successful for subclavian
vein procedures (1.48, 1.03 to 2.14). No significant
difference was found between these techniques for
cannulation of the internal jugular vein in infants. An
indirect comparison of relative risks suggested that
two dimensional ultrasonography would be more
successful than Doppler guidance for subclavian vein
procedures in adults (0.09, 0.02 to 0.38).
CONCLUSIONS: Evidence supports the use of two
dimensional ultrasonography for central venous
cannulation
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